A Cure for the “Radiation Space Travel Blues”?

Science magazine has just published a peer-reviewed article examining the radioprotective (or anti-radiation) abilities of an emerging class of drugs. [1] This follows the recent announcements that two pharmaceutical/biotech companies have received government funding to further develop their respective anti-radiation drugs. According to the announcements for the research awards, the US Department of Defense is seeking anti-radiation drugs that can be used to treat soldiers who are exposed to radiation. My initial thought with respect to this news, however, is that such anti-radiation drugs also may help solve one of the largest challenges associated with interplanetary travel — in fact, the development of anti-radiation drugs could be as important to human spaceflight as the development of the spacesuit. 

Although it is much more frequently discussed in the technical literature than in the popular media, the simple fact is that the high radiation levels permeating outer space make travel beyond low Earth orbit a potentially deadly affair. A 2003 NASA report called interplanetary ionizing radiation “the most significant factor limiting human’s ability to participate in long duration space missions.” [2] The astronauts living on the International Space Station (ISS) receive between 40 and 80 times the amount of radiation as their counterparts who remain on Earth, despite the fact that the fact that the ISS orbits well within a zone of natural radiation protection provided beyond Earth’s magnetic field. Move outside of Earth’s magnetic field, such as astronauts would on a trip to the moon or Mars, and radiation levels can jump ten to one hundred times beyond the levels encountered at the ISS. [3]

The planning for longer space missions in the future, including NASA’s current plans to return to the moon with stays on the lunar surface lasting weeks or even months, actively attempts to address the radiation issue. For example, such remedies have been considered as surrounding the living areas of spacecraft with bulky equipment (to serve as shielding from incoming radiation), adding significantly thickened shielding to spacecraft skins, and in the case of lunar habitats burying the primary living/sleeping quarters under several meters of lunar soil (again, to act as shielding). In the case of spacecraft, such solutions have limited use because any increase in the weight of the spacecraft (due to added shielding materials) also increases the fuel needed to move the spacecraft, which in turn drives an exponential increase in costs.

So the concept of a drug that can lessen, negate or even prevent the effects of high-level radiation exposure would seem like a godsend for human space travel. But what exactly is the reality of the radiation research currently underway?

On April 3, the Department of Defense awarded an $8.9 million contract to Cleveland BioLabs (located in Buffalo, not Cleveland ...) to further develop its anti-radiation drug called Protectan. Earlier in January, the DoD had awarded a $225 million contract to Osiris Therapeutics for the development of their own anti-radiation treatment. Based on the news coverage and press releases associated with these research contracts, the goal is twofold; both radiation resistance (taking a drug before exposure to prevent future damage from radiation) and radiation treatment (taking a drug after exposure to repair any radiation-induced damage that has already occurred). For long-term space travel, both of those processes could play an important role.

One unknown that remains to be determined is whether drugs (or for that matter, any other new treatment) designed to prevent and treat radiation damage related nuclear weapons and terrestrial radiation threats would also be effective against the space radiation environment. I’m not an expert in particle physics or radiation, but I suspect there might be some basic differences between the radiation you experience when someone drops an H‑bomb down the road from you, and the radiation you experience while floating halfway between Earth and Mars.

So although it is very early in the development of these drugs, there does seem to be some potential for their application in human space travel. This definitely is a development to watch and see what arises.

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1. “Drug Bestows Radiation Resistance on Mice and Monkeys,” Sciencemagazine, 11 April 2008

2. “Space Radiation Part 2: Learning from Experiments in Space,” NASA Office of Biological and Physical Research, October 2003.

3. The radiation exposure an astronaut experiences tends can fall within a wide range, depending on several factors — including location within (or outside of) the Earth’s magnetic field, time during the 11-year solar cycle, the individual astronaut’s susceptibility and how much time is spend spacewalking (outside the spacecraft). A good introduction to the subject for the average person is the short NASA publication “Understanding Space Radiation,” October 2002, and available for download here.